1. Field of the Invention
The present invention relates to a method for controlling advanced-function universal personal telecommunication (UPT) services.
2. Description of the Related Art
In recent years, UPT services have been studied with regard to new telecommunication service techniques by the CCITT (Consultative Committee for International Telephony and Telegraphy) and others. The UPT services are designed to provide subscribers with a variety of services using personal numbers assigned them through a public exchange network. An implementation of the method for controlling the UPT services at a realistic level is desired.
Although the UPT services are still being studied by the CCITT, it is said that they will provide subscribers with such communication services as calling other subscribers using personal numbers assigned them as well as their telephone numbers. PTNs (Personal Telecommunication Numbers) which are different from conventional telephone numbers (also referred to as DNs (Directory Numbers)) are special for subscribers. When a sending subscriber dials the PTN of a receiving subscriber, the former can access the latter. Moreover, when a sending subscriber dials a special number for a PTN charging service, the connection charge for a call that follows is charged to his PTN rather than the DN with which he will call.
These services will be provided by a new network system referred to as an AIN (Advanced Intelligent Network), which is an improved system of the new network system referred to as an IN (Intelligent Network).
Of the UPT services, the following service is known. In an exchange network where the terminal number (telephone number) of a telephone set and so forth of a receiving subscriber according to his PTN has been registered, when a sending subscriber dials the PTN of the receiving subscriber, the DN according to the PTN is retrieved from the network and then the telephone set of the sending subscriber is connected to the telephone set of the receiving subscriber so as to call the receiving subscriber.
However, in this service controlling method, if a receiving subscriber who is going from one site to another site is called or if an access to a subscriber who is not at a registered site is attempted, when the network calls a telephone set registered to the receiving subscriber since the receiving subscriber cannot answer the call, the sending subscriber cannot communicate with the receiving subscriber.